(1) Field of the Invention
This invention relates to tongs for gripping and holding cylindrical goods.
(2) Description of the Prior Art
Tubing and rods used in the bore of wells are comprised of many lengths or joints threaded or connected together to form a string. Equipment for threading and unthreading such lengths, or making up or breaking down the string, ordinarly includes a holder or tong for holding the string within the bore stationary while a spinning holder or tong rotates a length or joint of tubing in threadable alignment with the string. Such makeup or breakdown operations ordinarily involve large forces and heavy equipment.
Some holders or tongs in common use are manually locked and operated. On occasion, the person holding or operating the holder is injured because of his proximity to the makeup or breakdown operations and equipment when something slips or breaks.
Before this application was filed, a search was made in the U.S. Patent and Trademark Office. That search developed the following U.S. Pat. Nos.
______________________________________ PAGENT 2,760,392 HAM ET AL 3,518,903 BARRON ET AL 3,780,815 GUIER 3,799,009 ECKEL 4,082,017 KINZBACH 4,346,629 ______________________________________
These patents are considered pertinent because the applicant believes the Examiner would consider anything revealed by the search to be relevant and pertinent to the examination of this application.